This invention relates generally to conduit swivels and more particularly to a ball and socket type pivot joint for use in lines where swiveling of the joint under pressure is required. A one-way brake can be fitted to the pivot joint to enable a heavy nozzle to be carried by the pivot joint without the nozzle's elevation being lowered by gravity.
Firefighting monitors are devices used to deliver large volumes of firefighting fluid such as water or foam. A monitor has an inlet that is connected to a feed hose or a pipe, and a discharge to which a nozzle is fitted. Some means is provided to vary the direction of the nozzle so that a stream of fire fighting fluid can be moved in both the horizontal and vertical directions.
Some existing monitors use ball and socket type swivels to accomplish movement in the horizontal and vertical directions. Ball and socket swivels have only a few parts and are simple to manufacture and maintain as compared to swivels that use ball bearings, for example.
Ball and socket swivels typically have very direct flow passages that can result in less pressure loss in the firefighting fluid flowing therethrough. Further, ball and socket swivels usually enable movement in all directions, but they generally have a more limited range of motion compared to ball bearing type swivels.
Typically in ball and socket swivels, the socket captures the ball so that internal pressure from the firefighting fluid does not separate the joint. The axial load due to the internal pressure is born by the ball/socket interface, which causes friction drag in the swivel during redirection. When the fluid pressure in the swivel is high, the axial force can be so great that redirecting the swivel is difficult, if not impossible.
To alleviate some of the friction drag, a ball and socket swivel with an axle passing completely through the joint is taught in U.S. Pat. No. 4,392,618. The axle bears the axial force from the water pressure thereby overcoming the high friction of a ball being pressed into a socket. Unfortunately, the presence of such an axle or other obstruction in the fluid conduit leads to turbulence and pressure loss in the fluid.
Regardless of the type of swivel used, portable monitors have never before had the ability for the hoses to enter the monitor by means of a swiveling joint, and for good reason. Reaction forces in a monitor are axially aligned with the direction of the discharge stream from the nozzle. When a portable monitor and hose are on a relatively flat support surface, the monitor is generally stable because the reaction forces plus the weight of the monitor keep the monitor in stable contact with the support surface.
The stability of a portable monitor becomes questionable when used on uneven surfaces. For example, if a portable monitor were set at the bottom of a flight of stairs, the feed hose going down the stairs into the monitor could cause the monitor inlet to tip upwards in alignment with the hose in response to the hose stiffening when fluid starts flowing.
Further, when ball and socket type swivel joints are used on a monitor discharge, the weight of the nozzle will redirect the discharge downward. Spring clutches on rotary valves are known, as in U.S. Pat. No. 3,940,107, but one-way brakes on pivoting conduit joints that permit an operator to easily redirect the nozzle are unknown. Thus, swivels on monitor outlets are problematic, as well.
Thus, an improved swivel is needed that does not have the above-described problems.